A Chinese engineer was charged with stealing secrets from a stealth self-driving vehicle project at Apple, a freshly unsealed criminal complaint revealed.

Jizhong Chen was arrested in January, a day before he was booked on a flight to China where he had applied for a job with an autonomous car company, according to the criminal complaint filed this week in US court in California.

The trade secrets theft charge against Chen carries a maximum penalty of 10 years in prison and a fine of US$250,000.

Chen, an electrical engineer, was hired by Apple in June of last year to be part of a hardware design team working on a self-driving car project at Apple, FBI special agent Adelaida Hernandez said in the filing.

Chen was given “secrecy training” in how to avoid leaking information, even to family members, and was one of about 1200 “core” employees with access to the building where the project was centred, according to the complaint.

In December, Chen was put on notice by Apple that his work performance needed to improve. The next month, a co-worker noticed Chen taking photos of the self-driving car project and alerted superiors, the filing said.

An internal investigation determined that Chen had taken pictures of the stealth project and backed up his Apple work computer to a personal machine, along with more than 2,000 files including schematics, manuals and diagrams, according to the complaint.

People familiar with the matter have previously said Apple’s project to develop an electric self-driving car included hundreds of employees but reports have hinted at major troubles. Picture: Michael ShortSource:Bloomberg

Chen told Apple he downloaded his work computer to a personal computer as an “insurance policy” for job prospects in case his performance-improvement-plan at Apple ended with his termination but some photos dated back to June, Hernandez said in the filing.

Chen was suspended from his job as a result of Apple’s internal investigation, findings from which were shared with the FBI.

In July of last year, an ex-Apple engineer was charged with stealing secrets from the hush-hush self-driving car technology project days before he quit to go to a Chinese start-up.

Xiaolang Zhang was accused stealing trade secrets from the Apple project, according to a copy of the criminal complaint posted online.

The two cases did not appear related, according to the filing by Hernandez. Apple last week indicated it was trimming its autonomous car team but that it remained committed to the technology.